Determination of free clindamycin, flucloxacillin or tedizolid in plasma: Pay attention to physiological conditions when using ultrafiltration.

Pharmacokinetic/pharmacodynamic indices of anti-infective drugs should be referenced to free drug concentrations. In the present study, clindamycin, flucloxacillin and tedizolid have been determined in human plasma by HPLC-UV. The drugs were separated isocratically within 3-6 min on a C18 column using mixtures of phosphate buffer-acetonitrile of pH 7.1-7.2. Sample treatment for the determination of total drug concentrations in plasma included extraction/back-extraction (clindamycin) or protein precipitation (flucloxacillin, tedizolid). The free drug concentrations were determined after ultrafiltration. An ultrafiltration device with a membrane consisting of regenerated cellulose proved to be suitable for all drugs. Maintaining a physiological pH was crucial for clindamycin, whereas maintaining body temperature was essential for tedizolid. The methods were applied to the analysis of total and free drug concentrations in clinical samples and were sufficiently sensitive for pharmacokinetic studies and therapeutic drug monitoring.

Isolation and identification of two unknown impurities from the raw material of clindamycin hydrochloride.

Clindamycin hydrochloride belongs to the antibiotic family of lincomycin. It has the same antibacterial spectrum as lincomycin, but the antibacterial activity is four to eight times stronger than that of lincomycin. There have been some adverse reactions in clinical use of clindamycin hydrochloride and its finished drug products. The impurities in drugs are directly related to their safety. In this study, two unknown impurities were isolated from the raw material of clindamycin hydrochloride through various chromatographic methods. Their structures were identified as clindamycin isomer (impurity 1) and dehydroclindamycin (impurity 2) by mass spectrometry and NMR spectroscopy. Both of them were found for the first time. The two impurities exhibit a similar but lower antibacterial activity compared with clindamycin hydrochloride.

Facilitated column selection in pharmaceutical analyses using a simple column classification system.

In this paper, the performance of a previously developed classification system applied to pharmaceutical chromatographic analyses, is investigated. The separation of seven different drug substances from their respective impurities was studied. The chromatographic procedure for acetylsalicylic acid, clindamycin hydrochloride, buflomedil hydrochloride, chloramphenicol sodium succinate, nimesulide and phenoxymethylpenicillin was performed according to the corresponding European Pharmacopoeia (Ph. Eur.) monograph. The separation of dihydrostreptomycin sulphate was performed according to the literature. It is shown that the column ranking system is a helpful tool in the selection of a suitable column in these analyses.

Recovery of clindamycin from fermentation wastewater with nanofiltration membranes.

Experiments were carried out on clindamycin's separation and recovery from clindamycin fermentation wastewater with nanofiltration (NF) membranes. Four types of flat-sheet NF membranes, DLNF-1, NTR-7250, XCNF-1 and MPF-44, were tested under different dynamic operating conditions. It was found that the operating pressure and solute concentration had great influence on membrane performance while flow rates (or velocities) had little influence on membrane performance. Experiments on SO4(2-) rejection were conducted with such four flat-sheet NF membranes because SO4(2-) had bad influence on microbes in biochemical process following the NF process. The results indicated that DLNF-1 and MPF-44 membranes had higher SO4(2-) rejection among four membranes. Two spiral membranes, MPS-44 (1.4 m2) and DLNF2-30 (0.24 m2), were adopted in a concentrating process for clindamycin's separation and recovery from clindamycin fermentation wastewater under laboratory conditions. After being operated for 60h, clindamycin wastewater was concentrated from 266 to 26L, and the clindamycin was concentrated from 220 to 1940 mg/L, which met the demand of reuse. This research may widen the application of NF membranes in disposal of pharmaceutical wastewater.

Determination of clindamycin in human plasma by liquid chromatography-electrospray tandem mass spectrometry: application to the bioequivalence study of clindamycin.

A simple, sensitive and specific liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) method for the determination of clindamycin (I) was developed. Both I and verapamil (II, internal standard) were analyzed using a C18 column with a mobile phase of 80% acetonitrile-0.01% trifluoroacetic acid. Column eluents were monitored by electrospray tandem mass spectrometry. Multiple reaction monitoring (MRM) using the parent to daughter combinations of m/z 425-->126 and 455-->165 was used to quantitate I. A limit of quantitation of 0.0500 microgram/ml was found. The assay exhibited a linear dynamic range of 0.0500-20.0 micrograms/ml and gave a correlation coefficient (r2) of 0.998 or better. The chromatographic run time was approximately 2 min. The intra-batch precision and accuracy of the quality controls (QCs, 0.0500, 0.150, 1.50, 15.0 and 20.0 micrograms/ml) were characterized by coefficients of variation (CVs) of 5.13 to 13.7% and relative errors (REs) of -4.34 to 4.58%, respectively. The inter-batch precision and accuracy of the QCs were characterized by CVs of 4.35 to 8.32% and REs of -10.8 to -4.17%, respectively. The method has successfully been applied to the analysis of samples taken up to 12 h after oral administration of 300 mg of I in healthy volunteers.

Liquid chromatography method for separation of clindamycin from related substances.

A reversed-phase liquid chromatography method has been developed for the separation of clindamycin from 7-epiclindamycin, clindamycin B, lincomycin, lincomycin B, 7-epilincomycin and other impurities of unknown identity. The method uses a Hypersil ODS, 5 microm, 250 x 4.6 mm i.d. column maintained at 45 degrees C. The mobile phase comprises acetonitrile phosphate buffer (1.35% v/v phosphoric acid, adjusted to pH 6.0 with ammonium hydroxide)-water (35:40:25, v/v) at a flow rate of 1.0 ml/min. UV detection is performed at 210 nm. The method was tested on several C-18 columns and showed good robustness. Robustness was further evaluated by performing a full-fraction factorial design experiment. The method showed good selectivity, linearity, and repeatability. It is also suitable for analysis of clindamycin formulations.

Determination of clindamycin in pharmaceuticals by high-performance liquid chromatography using ion-pair formation.

A reversed-phase ion-pairing high-performance liquid chromatographic procedure with refractive index or UV 214 nm detection was developed for the separation of clindamycin, clindamycin B, and 7-epiclindamycin. The chromatographic retention behavior of these compounds on an octadecylsilane column was investigated as a function of pairing-ion, mobile phase composition, and pH. The method was applied to the determination of clindamycin in bulk drug and in a number of pharmaceutical formulations. The relative standard deviations for all assays was in the 0.5-2% range.

Microbial transformation of antibiotics. Clindamycin ribonucleotides.

Addition of clindamycin to whole-cell cultures of Streptomyces coelicolor Müller resulted in the loss of in vitro activity against organisms sensitive to clindamycin. Incubation of such culture filtrates with crude alkaline phosphatase generated a biologically active material identified as clindamycin. Fermentation broths containing inactivated clindamycin yielded clindamycin 3-ribonucleotides and clindamycin 3-phosphate the structure of which was established by physicochemical and enzymatic means. Attempts to transform clindamycin to clindamycin 3-ribonucleotides by lysates or partially purified enzyme preparations from S. coelicolor have failed.

Use of electrophoresis in the identification and quantitation of antibiotics administered in combinations.

The investigation presents a method of electrophoretic separation of antibacterial drugs which are used in combinations in clinical medicine. Subsequent to electrophoresis in agarose gel, a microbiological assay was performed. This technique permitted the determination of the concentrations of beta-lactam antibiotics, rifampicin, and clindamycin in the presence of aminoglycosides. In therapeutic combinations of fusidic acid and clindamycin, the concentrations of each drug could be determined.

Liquid chromatography of clindamycin 2-phosphate on triethylaminoethyl cellulose.

The separation of clindamycin 2-phosphate from clindamycin 3-phosphate, clindamycin 4-phosphate, clindamycin B 2-phosphate, and lincomycin 2-phosphate was achieved by liquid chromatography on triethylaminoethyl cellulose using a 254-nm monitor. The compounds have low molar absorptivities at 254 nm (smaller than 17), and UV detection is made possible by the high capacity support triethylaminoethyl cellulose. Linear peak height response versus concentration allows rapid quantitation of clindamycin 2-phosphate.